Ukraine has said Russia launched a "massive" overnight attack on energy infrastructure in the west and south, adding that at least seven people died from Moscow strikes elsewhere.
Russia launched 16 cruise missiles from land, sea and air as well as 13 attack drones, aiming at energy infrastructure in several regions, Ukraine's military said.
Air defences downed all but four of them, it added.
Russia's defence ministry said that its troops "carried out a group strike with long-range high-precision weaponry from air and sea and also drones on Ukrainian energy facilities that power arms production".
It said it also targeted warehouses containing munitions and "air-launched weapons provided to the Ukrainian military by western countries".
"All the set targets were hit," the ministry said, calling its latest attacks retaliation for Ukrainian attacks on its own energy network.
The Ukrainian energy ministry said this was Russia's "eighth massive, combined attack on energy infrastructure facilities" in the past three months, targeting the southern Zaporizhzhia region and Lviv in the west.
"Equipment at (operator) Ukrenergo facilities in the Zaporizhzhia and Lviv regions was damaged," the ministry said.
Ukrenergo said that two employees were wounded and hospitalised in Zaporizhzhia, where Europe's biggest nuclear plant is located.
More than two years into the Russian invasion, targeted missile and drone attacks have crippled Ukraine's electricity generation capacity and forced Kyiv to impose blackouts and import supplies from the European Union.
Ukrenergo said outages across the country would start earlier than usual today, running from 11am to 9am, due to damage from the attacks.
Meanwhile, three people were killed and 29 were wounded when Russia bombed a residential building in Ukraine's northeastern city of Kharkiv on Saturday.
Ukraine's President Volodymyr Zelensky posted footage of the torn-off facade of an apartment block and a crater outside.
"Russian terrorists have again hit Kharkiv with guided bombs," he wrote on Telegram after the latest attack on Ukraine's second largest city, announcing three dead while rescuers still cleared debris.
In Zaporizhzhia, shelling over the last day also killed one civilian and destroyed residential buildings and infrastructure, according to the regional military administration.
Russia controls a part of the region and the nuclear plant. The Russian-appointed administration said Ukrainian attacks had damaged a substation linked to the city's nuclear power plant but did not affect nuclear safety.
Maksym Kozytskyi, the governor of the western Lviv region, said Russia "launched a missile attack on a critical energy infrastructure facility", sparking a fire that was later extinguished.
Ukrainian troops based in the west shot down seven out of 10 cruise missiles fired by Moscow, the Lviv regional governor said.
Russian attacks have destroyed half of Ukraine's energy capacity, according to President Volodymyr Zelensky.
Mr Zelensky said this week that all hospitals and schools in Ukraine must be equipped with solar panels "as soon as possible".
"We are doing everything to ensure that Russian attempts to blackmail us on heat and electricity fail," he said on Thursday.
DTEK, the largest private energy company in Ukraine, said Thursday that strikes caused "serious damage" at one of its plants.
DTEK chief executive Maxim Timchenko warned that Ukraine "faces a serious crisis this winter" if the country's Western allies do not provide military aid to defend the energy network.
Mr Zelensky has repeatedly urged Ukraine's allies to send more air-defence systems to protect the country's vital infrastructure.
Front-line clashes were ongoing Saturday in the area near the town of Pokrovsk, northwest of the Russian-controlled city of Donetsk, where Moscow is trying to break through Ukraine's defences, Kyiv's military said.
Russia's defence ministry said troops had improved positions in the eastern Donetsk and Lugansk regions and northeastern Kharkiv region.
Five civilians were killed by Russian shelling in frontline areas of the Donetsk region, the head of the region, Vadym Filashkin said.
In the southern Kherson region, a policeman manning a checkpoint was killed by a drone, Ukraine's national police force said.
Russia's defence ministry said it had hit 340 Ukrainian targets over the past day.
The head of Russian authorities in the Donetsk region, Denis Pushilin, said the separatist-controlled city of Donetsk and the nearby town of Gorlivka had come under heavy attack from Ukraine.
Three men working for a construction firm were killed by a rocket releasing cluster munitions, he said.
Three more were wounded by a drone attack on a civilian minibus, Mr Pushilin added, and another man was wounded by an anti-personnel mine.
In Russia's southern Belgorod region, a man was killed by shelling of an agribusiness near the border with Ukraine's Kharkiv region, said governor Vyacheslav Gladkov.
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